Broach



Jan. 2, 1923.

J. L. PERKINS ET AL.

BROACH.

ORIGINAL FILED 0c 2 SHEETSSHEET E.

WITNESS:

A TTORNE) Jan. 2, 1923. 1,440,933.

.l. L. PERKINS ET AL. BROACH.

ORIGINAL FILED OCT- 28, 1919- 2 SHEETS-SHEET 2- WITN S:

ATTO

' aaaaeaa PATENT oeeica;

JULTAN L.- PERKINS, OF WEST SPRINGFIELD, AND FRANK w. SICKLES AND JOHNOAKLEY, 0F SPRINGFIELD, MASSACHUSETTS, ASSIGNORS o PERKINS APPLI- ANCE.COMPANY, OF- SPRINGFIELD,

MASSAC HUSETTS.

MASSAGHUSETTS, I A CORPORATION OF BROACH'.

Original application filed October 28, 1919, Serial No- 333,987. Dividedand this application filed Ju-ly 15, 1920. Serial No. 396,494.

v To all whonimay concern: Be it known that we,JULIAN .L. PERKINS,aresident ofjVest Springfield, in the county 20f Hampden and State ofMassachusetts,

FRANK TY. SICKLES, a resident. of Springfield'insaid county and State.both citizens of the United States of America, and JOHN OAKLEY,.asubject-\of the King of England, residingin said Springfield.Massachusetts. have invented a new and useful Broach, of

-which the following is a specification.

, Our invention relates to improvements in the art of Cuttingbevel-gears. spur-gears, racks, and the teeth in other elements-0f amore or less similar character. and resides in roughing or stocking andfinishing, cutting or broaching members or elements of peculiarconstruction, which are 1 designed especially for use inmultiplegear-cutting machines, such as that which forms the subjectof ourapplication for United States Letters Patent. filedOctober 28, 1919,Serial No. 333,987, of which this application is a.

divisional part.

The primary objectof our invention is to provide a broach for cuttingteeth in gear blanks accurately and expeditiously, which broach isdurable, and has superior faculties whereby it can be kept in. orderwith the minimum amount of labor and expense.

This broach is termed a compound broach or cutter for the reason that itcomprises roughing or stocking and finishing cutting or broachingmembers or elements as af0resaid. The compound broach or cutter is madeup of holding means and a row of teeth or cutting units therein. suchunits being readily removable therefrom and replaceable therein. Thereis a set of roughing or stocking cutting unitsin said holding means anda setof finishingcutting units therein behind said Stocking cuttingunits. These cutting units may be easily and cheaply constructed, andthey can be quickly changedwhenever necessary. It appears, therefore,that the compound cutter comprises a roughing or stocking cutter infront and a finishing cutter behind. the cutting units of-said stockingand finishing cutters being independent and separable.

Being separate cutting units they possess units to .cool.

advantages inherent or due to that fact. \Vith them more work can beperformed at one time than is possible with the ordinary gearcutting.elements, and the work done by said cuttingunits is accurate, becausethey are arranged, or backed up, so to speak, So that the cutting strainis on the units themselves when the compound cutter is engaged inactiveoperation. with the result consequently practically all chance of erroror irregularity due to any leading finishing cutting unit is removed andprevented from appearing upon or in the finishing product. The lastfinishing cutting unit, which makes the final cut. has very little stockto remove and consequently lasts a longer time without requiring to bereground or replaced. which is an important advantage because this isthe unit that determines the final size and shape of the cut.

Inasmuch as each stocking cutting unit makes but one cut at each strokeof the compound cutter of which such unit constitutes a part, and eachfinishing cutting unit makes but one cut at each stroke of said compoundcutter, there is ample time for the and the wear of the same isminimized.

The peculiar construction of the compound broach as a whole and of itscutting units permits a deeper cut tobemade than can be done with planerimplements, due to the fact that said cutting units are in line witheach other, one behind the other in the direction of operative movementor cutting action, and each is the full width and size of the slot whichis cut by the cutter of which the units form apart. that is to say. eachunit is capable of making a cut that is equivalent to By *providing aseries of roughing or stocking and a series of finishing cutting units,such as described above, a distinctive and most important advantageaccrues, in 5 that eachof such units removes a predeter- 'mined amountof metal from the same portion of the work at each stroke, the amountremoved by each succeeding unit 'bein slightly more than that removed byeac preceding unit; and the finishing units are saved from the wear andtear "and service of the stocking or roughing operation, and theircutting portions for partsmaintain or retain an accurate and sharpcontour for a I correspondingly longer period.

. The amount of material removed in a given time by our compound broach,as'

compared with the amount removed by either a rotary or a planer cuttingelement," is several trmesas great, for the reason that the successivecutting edgesof the rotary cutting elements are brought into action oneat a time, or at best two only are in contact at the same time with thestock to be removed, the one case, and the'planer cutting elementsremove only one comparatively small portion of the gear-tooth slot andonly a single cutting element is in action at one time, except in thedouble-planer machine where two may be in action, while with our broachasmany cutting units, each- 4 4o ting units, it would not be possible tostock and finish the work at one stroke, the great importance andvalueof -doing which is clearly apparent. k,

In our broached gear, the shape of the gear tooth corresponds exactlywith the' shape'of the last c uttingunit of the finishing cutter, or, tostate it difi'erently, the finishing cutter produces a slotinto whichsaid last unit fits, because the direction of movement of thecuttingunit ,in making its active stroke is in a straight line throughthe wor and said cutting unit \cannot cut a.

\ slot larger than itself. The advantage of this result over th'e'result produced byeither", a rotary cutter, or reciprocating planing,cutters that pass through and operate in the work on planes parallelwith the axis of the work is cleai when it is remembered. that eachcutting element, iii either of these cases may not pass in exactly thesame plane and will, therefore, make the slot icut thereby larger thanandof a different form from the one required. 'Inaccur'acy of thischaracter may be caused, also, when a cut- 65. ter does not run true onits arhor when end,-

p-lete lash is present in the machine spindle. when expansion of thearbor caused by warping is this true in the case of the reciprocatingplaning cutter which does not form a comear-tooth slot with each'stroke.but depends on a number of strokes to complete such a slot. The accuracyof the gear-tooth slot, in the latter case, depends entirely upon theaccuracy of the whole machine and of the path in which the planermembers are guided. A cutting element which is dull will spring awayfromthe work, if it come in contact with one side only of the slot,

while the full-width cutting unit cannot; pass through unless it have apath of 1ts 'own shape and size.

\Vhen the finishing cutter inour broach becomes worn, it is necessary toreplace only two or three of the last cutting units in order to maintainthe standard size and shape of the gear-tooth slot cut thereby.

It is not necessary to change the rouglr ing cutter, when cutting gearshaving different numbers of teetli*df the same pitch, I

but only to change the finishing cutter, re-' placing the latter withafinishing cutter having cutting units the curvatures of which correspondwith-the curvatures of the geartooth slots.

The roughing cutter is usually longer than the finishing cutter, that isto say. the former has more cutting units than the latter.

The type of the gear cut by this machine agrees exactly with that of thefinishing .possible'to do with; ourbro ach. "Entirecontour, as'used hereand elsewhere in the,

complete cutting edge of each cutting unit.

Another object is to provide means, where by the cutting unitsin theroughing cutter are all of the same size, length, and shape, and thecutting units in the finishing cutter are all of the. same ,size,length, and shape. This mater-ially reduces the initial cost of thecuttersjand also the cost of respecification, refers to the contour ofthe pairing them and of sharpening the cutting 12 5 units;

Still another object is to provide means for tilting or inclinlng theroughing and finishingcutters to produce the required depth ofslot, inconsequence of which it is pracconduits: Fig. 7

. tlng umt of the roughlng cutter,

' Fig. 11. an end elevation.

-of'the parts shownv in Fig. .10; Fig. 12, an

' tion. of thepart s' shown in Fig. 12: Fig. 14 a view similar to Fig.12 except that the fin- CJI . partial sct iolffoftlle .c'edlngvlew; J

whereby we obtain the objects and secure the advantages of the same. isillustrated in the accompanying drawings. and we will proceed todescribe said invention with'reference to said drawings, although it isto be understood that the form, construction, arrangement, etc. of theparts and members in various aspects are not material and may bemodified without departure from the spirit iof the invention..-

In the drawings, in which similar characters of reference designatesimilar parts throughout the several views, Figure l "is a sideelevation of a detached cutting unit; Fig. 2, an endelevation of suchunit; Fig. 3, a side elevation of a double cutting unit or two suchunits united or integral; F ig. 1, a

top plan of a compound cutter or broach which embodies a practical form,of our inventlon as aforesald Fig. 5, an end elevation of saidbroach,'th e oil conduits shown in the preceding -view being omitted.(this is really a left-hand elevation of Fig. 6'); Fig. 6, a frontelevation ofsaid broach. without said an enlarged. perspective view ofthe major portion of the finishing cutter of said compound broach, partsbeing in section; Fig. 8. anoperative view showing the cut made by thesecond; leading cuta fragmentary portion ofwhichlatter is shown in sideelevation and a bevel-gear blank in section; Fig. 9. an end elevation ofthe parts shown in Fig. 8 as viewed from the rightj parts of theroughing cutter being in section; F ig.

10. a view similar to Fig.

8, but showing the roughing cutter about to complete its cut; in partialsection,

operative view illustrating the early opera the view being 8:, Fig. 13.an" end elevation. in partial secishing cuttr'is about to complete thegeartooth slot. and Fig. 15. an end elevation, in

parts shown inthe' pre The'c'ut-tingunit shown in Figs. 1 and 2 is i oneof the cutting units in the roughing cut- ,ter of the compound broachillustrated Figs. 4. 5. 6, and 7.

portingmember or support 1. and a" rough ing or stocking cutter and afinishing cutter mounted on and attached to sa d support. said roughingandfinishing cutters comprising. respectively. independent, removablecutting units 2 and 3. The support 1 is angular in cross section. anddesigned to be securelyattached to a bed-plate or other member of. themachine in which the compound broach is employed, and which bed-plate ormember is adapted to carry the broach, or to support the same in theevent of the machine being constructed so that the work travels insteadof the ..broacl. Bolts 4 andshort splines 5 may be provided for'securelyattaching the support 1 to its 'bed plate or other member.

. The roughing cutter and the finishing closely and intimately connectedand assomated therewith. having especial referenceto Fig. 7, isapplicable to the holder 6 with its connected and associated members.

The holder 7 has a forwardly-extending.

longitudinal lip or flange8 at the bottom.

the top of which flange inclines from within outwardly and downwardly,and said holder has a forwardly-extending, longitudinal lip or flange 9at the top, the under side of which latter flange inclines from withinoutwardly. Preferably the top of the flange 9 has a more or less similarinclination to that of the bottom of said flange for clearance purposes.upright part of the holder 7 is a finished ..'rib or backing piece 10for the cutting units 8. Each cutting unit 3 has in what may be termedthe backside thereof, at the top. a V- sha'ped groove 11 (see Fig. 2).which elvtends from end to end-of said unit, and is adapted to receivethe acute-angled part of the flange 9. An end block 12 is provided atthe right-hand end of the row of cutting units 3, and an end block13 isprovided at the left-hand end of such row. These blocks are notas highas the cutting units 3. and their outer ends are vertical. while bothends j of each of said units are oblique. but otherwise said blocks areof the same general shape and construction as said units. \Vhen thecutting units 3 and the end blocks 12 and 13 are, in engagement with theflange 9, and with the inner or backsides of said units and blocksagainst the rib 10, the. underside's of said units and, blocks inclineoutwardly and upwardly from their lower rear or inner edges, and awedgebar 14 is introducecL The compound broach consists of a supbetween theflange 8 and said units and latter said bolts 7, respectively, Theholders On the inside face of the '3 and the blocks 12 and 13. aha Sehold said bar andcause the latter to crowd said units and blocks tightlyinto contact with the flange 9 and the rib 10', so that it is impossible under ordinary conditions for said units and blocks to becomedisplaced in the slightest degree. Upon loosening thebolts andv therebythe wedge bar 14, either or both end blocks can be removed and re-'placed, so that any of the cutting units can be taken outand replaced.

The imrts and members of the holder 6 which correspond with the partsand memend. 1 v

the absence of holding or securing bers of the holder Texcept- 1n thematter of length. are designated as follows: The bottom flange at 16.the top flange at 17. the backing rib at '18, the end blocks at 19 and20. respectively, and the wedge bar at 21,;

the bolts for the wedge bar having the same numerals as before. Theoblique end of the cutting units 2 and 3,'of which mention has beenmade. impart a rearward pitch or inclinatlon to said units as a whole.toward the work, and the blocks 12 and 19, therefore. incline from thebottom upwardly and toward the left at their left-hand ends. while theend blocks 13 and 20 incline from the top downwardly and toward theright at their right-hand-endsl The outer ends of the blocks 19 and 20.as well as the corresponding ends of the blocks 12 and 13, are

vertical. and all may be flush with the adjacent ends of the wedge bars.

It is to be understood that the compound means of the characterhereinbefore described, or of some other more or less similar character,it would be necessary to construct the cutting elements with the mem'bers, which are 7 now separable. wholly or partially integral. or, inother words, with the cutting units integral; with a Shank or holder, orintegral with some member which could be attached to a holder orvequivalent member of some description; thus adding greatly to theinitial cost and to the upkeep of the cutting elements.

Referring again to Fig. 7, itwill be seen that eachof the cutting unitshas a horizontal oil passage 22 and an upwardly direct-ed oil passage 23therein, the latter opening into the former at the bottom and throughthetop of the unit at the upper end.

' Eachof the end blocks 12 and 13 has a hori zontal oil passage 22therein, which connects with the passage 22 in the contiguouscuttingunit 3. .Similar-oil passages are provided ih the cutting unit 2and the blocks 19 and 20. Oil is supplied through pipes 24' and 25 tothe end blocks 12, 19 and 20, with rectly communicate. Oil is pumped orotherwise forced into the pipe 24 and thence into the pipes 25 and thepassages 22 and 22 t4) escape through the passages 23. The pipe v24extends parallel with the supportl,- and beside the roughing-and fin-1shing cutters. The pipes 25 extend from the pipe 24t0 the end blocks asalready ob-' served, or rather to the end blocks 12. 19."

the passages 22 in which said pipes 25 di-.

additional pipe 25 is plugged as shown at- V the oil supply tromv saidblock.

The oil forced through ,the pipes 24 and 25 into the end blocks 12,19,and 20 passes into and through the cutting units 3 and 2, escaping atthe top of such'funit behind, in the direction otthe cutting stroke ersaid units, the upper cutting edges thereof, and therefore, lubricatessaid units .to the re quired extent, discharging the lubricant at andimmediately adjacent to the points where the cutting operations aretaking place, which are e the most advantageous points for lubricatingpurposes. "At the same time the lubricant assists in carrying away thechips cut bythethecutting units.

It is assumed here, and generally so assumed throughout. thisdescription, that the compound broach moves while the. work is sta- Ltionary, although as has been stated said broach might be heldstationary while the work was caused tomove.

Each cutting unit 2 and 3 has therein a chip-clearance passage 27.Thepassage 27 is formed in the side of the cutting unit, be-

hind, in the direction of travel of said unit in the side which isopposite to that wherein the V-shaped groove 11 is located. The rela-"tive positions in the cutting units of the oil 1 15. when making itscut, from the approximate passages 22 and 23, the groove 11, and'thechip-clearance Passage 27, and the aforesaid cutting part 0 sald unitare clearly shown in- Fig. 2. It will be. observed that. the

passage 23 is smaller than the passage 22, the reason for which.iso'bvious. The cutting part of each unit 2 is indicated by the numeral28, and such part ofeach unit, 3 is indicated by the numeral 29.

40 wardly .The'roughing. and finishing cutters have to be tilted orinclined to the horizon sufli cientlv to obtain with their cuttingunits, which are. all of thesame height, the-re- 5 quired depth of slot,and to this enda plurality of horizontal bolts or cap-screws 33 andwashers 30, a horizontal bolt 31, washer 32, and nut 34, and a pluralityof vertical, 1 adjusting screws 35 are provided, and a .1 seriescofhorizontal slots 36 are formed in p the vertical part of the support 1.Theslots- 36 o enthrough the top of the upright part of t e support 1.In the present case there is a cap-screw 33 and -a screw 35 at each endof the roughing and one of each at each end of thefinishing cutter, andin addition to the said screws'for said roughing cutter the bolt 31,washer 32, and nut 34 are provided. The washers 30 are introducedbetween the heads of the cap-screws 33 and the adjacent sides of theupstanding part of the support 1, and the washer'32 is introducedbetween the head of the bolt 31 and said part of said support. Thecap-screws 33 and the bolt 31 am received in the slots 36, and saidcapscrews are tapped intothe holders 6 and 7, while the bolt 31 passesthrough said holder 6 and its wedge bar 21 to receive the nut 34 outsideof said bar. The purpose of the bolt 31 and nut34 is to prevent-thecentral part of the long roughing cutter from springing outwardly fromthe upright part of the support 1. The slots 36 are of sufficient sizeto enable the cap-screws 33 and the bolt 31 to be moved therein towhatever extent may be necessary in order to give to. the roughing andfinishing cutters the proper incline. The bolts 35 are tapped into andextend through the holders 6 and 7, passing downbehind the end blocks12, 13, 19, and 20, and bear at their bottom ends on the horizontal partof thesupport 1, or on bearing members 37 set in such horizontal part.The holders.6 and 7 and the cutters, of

l which such holders constitute parts, are adjusted at the requiredangle to thehorizontal part of the support 1, by turning the screws 35up and. down as may be and to-theextent required. This is done afterlooseningthe or inclining the two cutters at the proper angle or angles,by means of the screws 35, thecap-screws 3.3 are retightened and the nut34 is retightened on the. bolt 31. Co

cap-screws 33andthe nut 34. After tilting 5 venient and accurate meansare thus afforded for adjusting at any time the. roughing and finishingcutters to'the requiredangle or angles. andfor securelylhol-ding themaftersuch adjustment.

The proper adjustment units WlllCll intervene. It isnow clearly to beseen how we are able to utilize compound cutters or broaches which haveroughing and finishing cutters each with cutting units slot'cu't by saidunits in conjunction with the v of the same size and heightor depth.Otherwise it would be necessary to .employ in each cutter cutting unitsof different sizes or at least of difi'erent heights or depths.

Although we 'prefe'rrto employ cutting units which have a singlecuttingp art 28 (or 29) andasingle chip-clearance passage 27 such partand such passage may be duplicated in a single unit as shown in Fig. 3,and it might, in some cases, be feasible to provide a cutting unit witheven more than two of the parts and .passages in question. The

compound unit shown in Fig. 3 naturally has an oil passage 23 to openthrough each cutting part 28 ,,in the event the oil passages beprovided. 1

The cutting part 28, of eachcuttingunit 2, is narrower than the finishedslot in the gear blank which is cut in part by said unit, while thewidth of the cutting part 29, of each cutting unit=3, is of'the width ofsaid slot and with its companion cutting unit makes the finishing vcutwhereby said slot is produced. The cuttingunits 2 first cut the slotof the proper depth, but of a slightly less width than is required forthe finished-slot, and usually without curvatures therein, and then thecutter 3 takesoffa little on both sides-of the slot'cut by said units 2,thus cutting saidslot to width and at the same time .forming the curvesin the sides of said slot ginning of its operation on a gear blank 38,

wherein the leading cutting units 2, in the direction of the compoundbroach when advancing, are making their initial cut in said blank, whilein Figs. 10 and 11 the rearmost,

. tion and the slot is being materiallydeepened. and short-l will be ofthe required depth, substantial y as is represented at 39 in Figs.

following cutting units 2 are coming into ac- 11, 12, and 13. The slotwhile in the process of being roughed out is represented at 60 of eachcutter requires that the distance between-'the plane of the top of thecutting part (28 or 29), of the front or foremost cutting unit (2'or 3),and that of the top of such cutting part, of the rearmost cutting 65unit, be equalto the depth of the gear-tooth of the finishing cutter,isillustrate'd in Figs. 12 and 13, wherein the leading units arewidening, as represented at 41, the slot 40. In the last two views thecutting units 3, which are at or adjacent to the rear end of let Theinitial operation of the cutting units 3,

the finishing cutter, in the direction of travel in making its out, arealmost in the act of completing the slot 40 and converting it into atrue gear-tooth slot, substantially like that represented at 42 in Fig.15. I

The operationof the cutting units 2 and 3, and the manner in which gearblanks are cut therewith, will clearly be understood from the foregoingexplanation, together with the illustrations to which the samespecifically refers.

The lubricating means herein provided may be omitted, and some othermeans or method for lubricating the cutting parts may be substitutedtherefor. With this broach a complete gear-tooth slot is, cut everytimethat said broach advances to the full extent of its forward travel. a I

The compound broach-may be comparativelyshort, since it is necessary toprovide only a sufficient number of cutting units to obtain the requireddepth and width of slot Without undue strain on either said units or thematerial being cut, and without undue wear "and tear on said units, ithaving been found'thata great amount of accurate and satisfactory workcan be performed with 'a compound broach which iscOmparatively short andcomprises a comparatively small number of cutting units. It is bothpracti cable and possible to cut gears with this broach at a fairly highrate of speed. v

The cutting units in each set cut the full width of slot by asimultaneous action, to some extent at least, on all three sides of theslot. Although the finishing units enter the slot cut by the roughingunits, and do not. therefore, remove the central portions of thematerial from the slot, since that has already been removed, they do outand shape all three sides of the slot to a greater or less extent, and,in the absence of the roughing units, would cut away all of the materialto form the slot, so that said'finishing units are, to all intents andpurposes, of'the same nature as the roughing units, and are no moresimilar to a rotary cutter or milling tool, or a pair of planing toolsthan are the roughing 50 units I p a A portion of" the upstanding partof sup port 1 is broken away, in Fig. 5, in orderto' show 'morejclearly.one of the slots 36 and the cap screw 29;therein. whatiwecl'ai as ourinvention, and de- 1 sire to' -secure by Letters -Patent,is

1. A compound broach comprising a roughing cutter and a finishingcutter, said roughing cutter consisting in partof separa-- ble cuttingunits. 2. A compound broach comprising a roughing cutter, and afinishing cutter,- aid finishing cutter consisting in partof separableunits. l l

v 3. A compound broachfcomprising a "se arable cutting units of uniformheight,

and means to position said roughing cutter at an incline to saidsupport. I

6. A compound broach comprising roughing and. finishing cutters, asupport therefor, and ,means to position said finishingcutter at 'anincline to said support.

:7. A compound broach comprising a" roughing. cutter having teeth on oneside, and a finishing cutter having teeth on the corresponding" side, asupport for said ,cutters, and means to position said cutters ataninc-line to said support.

8. A compound broach comprising roughingand finishing cutters, a supporttherefor,- said roughing cutter co'nsisting in part of cutting units ofuniform height, and means toposition said roughingcut-ter at an inclineto said support. v i

9. Acompound broach comprising roughing and finishing cutters',,asupport therefor, said finishing cutter consisting in part ofcuttingu'nits of uniform height, and means toposition said finishingcutter at an iii-- cline to said support. I

10. A compound broach comprising roughing andfinishing cutters, a suport therefor. each of said roughing and finlshing cutters consisting inpart of cutting units of uniform height, and. means. to position saidroughing and finishing cutters at an incline to said support.-

11. A compound broach comprising rough- I ing and finishing cutters, asupport therefor, said roughing cutter consisting in part of an means toposition said roughing cutter at an incline to said support.

12. A compound broach comprising roughing and finishing cutters, asupport therefor; said finishing cutter consisting in part of 1separable cutting units of uniform height, andmeans to position saidfinishing cutter at an incline to said support.

13. A compound broach comprising roughing and finishing cutters, asupport therefor,

- each of thelatter consisting in part of separable; cutting units ofuniform height, and means to position said roughing and finishingcutters at an inclirfe to said support.

14. .The combination, in a broach, with a support, of a cutter sepuredto said sup-* port, said cutter comprising separable 'cutting-unit's,and means to position .said cutter on'said support at an incline theretowhich mess af thereto.

15. The combination, in a broach, with an angular support, of a cutter,adjustable means to secure said cutter to the vertical part of saidsupport, and adjusting means for said cutter to position the same at anincline to the bottom of said support.

16. The combination, in a broach, with an angular sup-port, of a cutter,bolts adapted tov secure said cutter to the vertical part ofsaidsupport, the latter being provided with slots for the accommodation of.said bolts, and bolts at the ends of said cutter to support said cutterfrom the bottom of said member at an incline thereto.

17. The combination,in a broach, with an angular support, of roughingand finishing cutters, means to attach said cutters tothe upright partof said support, and means at the ends of said cutters to support thesame from the bottom of said member at an incline .18. In a broach, aholder having a top flange which is angular in crosssection, and abottom flange which is inclined on, the upper side, a plurality ofseparable cutting units recessed to receive said angular top flange, andhaving tapered bottoms, a wedge bar receivable between said inclinedupper side of said bottom flange and said tapered bottoms of said units,and means to hold said wedge bar in place. I

19. In a broach, a holder having a top flange which is angular in crosssection, and

.a bottom flange which is inclined on the upper side, a plurality ofseparable cutting units and end blocks, each of said units and endblocks having recessed parts to receive said first-named flange,andtapered bottoms, a wedge bar receivable between the inclined part ofsaid bottom flange and said inclined bottoms, and means to retain saidwedge bar in place.

20. In a broach, a support, holders having upper flanges which areangular in cross section, and beveled under flanges, pluralities ofcutting units for each'o-t said holders, said units being recessed toreceive said up er flange, and being tapered on their un der sides, andwedge bars receivable between saidunder flanges and said under sides 'ofsaid cutting units, means to secure said wedge bars in place, and meansto secure said holders to said support.

21. The combination, ina broach, with an angular support, ofholders,pluralities of cutting units, means 'tosecure said cutting units to saidholders, and means to secure said holders to the vertical part of saidsupport, said holders being'arranged in line with each other on saidsupport.

22. The combination, in a broach, with an angular support, of holders,pluralities of cutting units, means to secure said units to saidholders, and bolts to secure said holders to the vertical part of saidsupport, the latter being slotted to'receive said bolts. j

23. A compound cutter comprising roughing and finishing cutters made upof separable units, and having longitudinal and lateral oil passagestherein, said lateral oil passages opening through the cutting parts ofsaid units, and said longitudinal oil passage being adapted to receivethe oil 'initiall line, and on one side only of a given plane to whichall of said cutting parts are approximately perpendicular.

25. A compound broach comprising a'single row of cutting parts capableof broaching a rudimentary gear-tooth slot in a blank, and, followingsaid row, a single row of cutting parts capable of finishing such slot,both of said rows being in the same straight line, and on one side onlyof a given. plane to which all of said cutting parts areapproximatelyperpendicular, and each of the cutting parts of saidfirst-named .row having the same amount of projection, beyond suchplane.

26. A compound broachcomprising a single row of cutting parts capableofbroaching a rudimentary gear-tooth slot in'a blank, and, followingsaid row, a single row of cutting parts capable of finishing such slot,both of said rows being in the same straight line, and on one side onlyof a given plane ing the -same amount of projection beyond such plane.

27. A. compound broachcomprising a single row ofcutting parts capable ofbroaching a rudimentary gear-tooth slot in a blank, and, followingsaidrow, a single row of cutting parts capable of finishing suchslot,both of said rows being in the same straight line, and on one sideonly'of a given plane to' which all of .said cutting parts areapproximately perpendicular, each of the cutting parts of saidfirst-named ro-w having the same amount of projection beyond such plane,and each of the cutting parts of said second-named row having the sameamount of projection beyond such plane.

JULIAN L. PERKINS. FRANK W. SIGKLES. JoHN OAKLEY. I

Witnesses: A. C. -FAIRBANKS. F. A. CUTTER.

